Name: reducing reactive power in ac loads
Uploaded: 2024-07-08T13:19:54.000Z
Duration: 1 min 20 s
Channel: JoVE

La transmisión de energía a una fábrica implica la transferencia de potencia activa y reactiva. La relación entre la potencia activa y la total define el factor de potencia.
Un factor de potencia bajo significa que la carga eléctrica inductiva absorbe más potencia reactiva, lo que provoca un factor de potencia rezagado bajo. Esto da como resultado grandes caídas de voltaje a través de la carga y pérdidas térmicas, lo que aumenta los costos de electricidad y reduce la eficiencia del sistema.
El factor de potencia se puede mejorar agregando una impedancia de compensación como condensadores autoajustables paralelos a la carga. Este enfoque hace que el factor de potencia se acerque lo más posible a la unidad.
El efecto de agregar el condensador se puede demostrar usando el triángulo de potencia. Al examinar el triángulo de potencia del circuito original, se puede determinar la potencia real y reactiva.
La adición de una carga capacitiva disminuye el ángulo del factor de potencia sin cambiar la potencia real. A partir del nuevo triángulo, se calcula el valor de la potencia reactiva corregida.
Esta reducción de la potencia reactiva es el resultado de la capacitancia de derivación. Al revisar las expresiones de potencia reactiva, se determina el valor del condensador de derivación.

corrección del factor de potencia

La transmisión de potencia a una fábrica implica la transferencia de potencia aparente, una combinación de potencia activa y reactiva. El factor de potencia mide la eficacia con la que la energía eléctrica se convierte en trabajo útil. La relación entre la potencia real (KW) que realiza el trabajo y la potencia aparente (KVA) suministrada al circuito.
<img alt="Equation 1" src="/files/ftp_upload/15123/15123_Equation_1.svg" style="height: 30px;">
Un factor de potencia deficiente significa que la carga eléctrica inductiva absorbe más potencia reactiva, lo que provoca un factor de potencia de retraso bajo. Esto da como resultado grandes caídas de voltaje en la carga y pérdidas térmicas, lo que aumenta los costos de electricidad y reduce la eficiencia del sistema. La corrección del factor de potencia se realiza ajustando el factor de potencia hacia la unidad para obtener un sistema eficiente. El factor de potencia se puede mejorar añadiendo una impedancia de compensación, como condensadores autoajustables, paralelos a la carga. El efecto de agregar el capacitor se puede demostrar usando el triángulo de potencia porque la potencia real y reactiva se pueden analizar examinando el triángulo de potencia.
<img alt="Equation 2" src="/files/ftp_upload/15123/15123_Figure_1.svg" style="height: 150px;">
Se agrega una carga capacitiva en serie o en paralelo y el ángulo del factor de potencia disminuye sin cambiar la potencia real. Se ajusta el valor del factor de potencia. Los condensadores en serie se utilizan para la corrección del factor de potencia en líneas de transmisión largas. Los condensadores conectados en serie contrarrestan la naturaleza inductiva de la línea proporcionando una corriente principal que puede neutralizar parte de la potencia reactiva retrasada y, como resultado, mejora el factor de potencia. Los condensadores en derivación son los más utilizados para la corrección del factor de potencia. Los condensadores están conectados en paralelo a la carga y proporcionan una corriente adelantada que compensa la corriente reactiva retrasada causada por las cargas inductivas. Esto acerca el factor de potencia general a la unidad. Al contrarrestar los efectos inductivos, los condensadores en derivación pueden reducir la cantidad de potencia reactiva extraída del suministro, haciendo que el sistema sea más eficiente.

Corrección del factor de potencia

La transmisión de energía a una fábrica implica la transferencia de potencia activa y reactiva. La relación entre la potencia activa y la total define el factor de potencia.
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Education

Educación

JoVE Core

Electrical Engineering

Ingeniería Eléctrica

Unit 1

Unidad 1

AC Steady State Power

Potencia de corriente alterna en estado estacionario

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

Power Factor Correction

reducing reactive power in ac loads

Power factor correction helps AC systems use electrical power more efficiently. In a factory circuit, transmitted power includes apparent power, which is made of active power and reactive power. Power factor is the ratio of real power, measured in kW, to apparent power, measured in kVA. It shows how much of the supplied power becomes useful work.

A low power factor often happens when an inductive load draws too much reactive power. This creates a lagging power factor. It can also cause large voltage drops across the load and thermal losses. As a result, electricity costs rise and system efficiency falls.

Power factor is improved by moving the value closer to unity. One way to do this is to add a compensating impedance, such as self-tuning capacitors, in parallel with the load. The change can be shown with the power triangle, where real power and reactive power are compared. A capacitive load can also be added in series or parallel, which lowers the power factor angle without changing the real power.

Series capacitors are used for power factor correction in long transmission lines. They counteract the inductive nature of the line by supplying a leading current that helps neutralize some of the lagging reactive power. Shunt capacitors are the most widely used option. They are connected in parallel with the load and provide a leading current that offsets the lagging reactive current from inductive loads. This brings the overall power factor closer to unity and reduces the reactive power drawn from the supply.

Reducing Reactive Power in AC Loads

instantaneous power

AC Power and Phase Shift

Instantaneous power in an electrical circuit comes from the voltage across an element and the current through it. It is written as p(t) and follows the passive sign convention. For sinusoidal input, this product helps show how power changes at each moment. When instantaneous power is expanded, it has two parts. One part is constant and depends on the phase difference between voltage and current. The other part is a sinusoidal term that varies at twice the frequency of the voltage or current. <br...

average power

Power Consumption in AC Circuits

Power consumption in AC circuits is often described with average power. In practical electrical work, the changing value of instantaneous power is less useful than the average over a time period. Average power is found by integrating instantaneous power over that time and then dividing by the duration. The time-domain expression for average power comes from simplifying the equation for instantaneous power. In that form, one cosine term averages to zero over a complete cycle. The result does...

effective value of a periodic waveform

RMS Value for AC Power Measurement

The RMS value, or effective value, helps measure how much power a periodic voltage or current can deliver. It is the direct current, or DC, value that gives the same average power to a resistor as the periodic signal does. This idea is especially important in AC circuits. To find the effective value of current, calculate the root mean square, or RMS, current. First square the instantaneous current values over one period. Then find the mean of those squared values and take the square root. The...

complex power

Power Triangle in AC Circuits

Power triangle and complex power help describe how an AC load uses energy. Engineers use complex power to capture the combined effect of parallel loads. It gives a full picture of the power consumed by a specific load. Complex power is found by multiplying voltage by the complex conjugate of current. Using rms values, it is written with the rms voltage phasor and the complex conjugate of the rms current phasor. It can also be written in terms of load impedance. The magnitude of complex power...

conservation of ac power

AC Power in Series and Parallel Circuits

AC power in series and parallel circuits follows a power preservation rule. In AC circuits, the complex power, real power, and reactive power produced by the source are equal to the total complex, real, and reactive powers absorbed by the loads. When two load impedances are connected in parallel to an AC source V, the source power can be written as the sum of the complex powers delivered to loads Z1 and Z2. If those same loads are connected in series with the voltage source, the complex power...

power factor

Power Factor and AC Load Behavior

Power factor describes how voltage and current behave in an AC load. It is the ratio of average, or active, power to apparent power. The power factor angle is the phase difference between voltage and current, and the cosine of that angle gives the power factor. It also matches the angle of the load impedance. Power factor shows how much apparent power becomes real, or average, power. Its value ranges from zero to one. When a load is purely resistive, voltage and current are in phase. In that...

power factor correction

Power factor correction helps AC systems use electrical power more efficiently. In a factory circuit, transmitted power includes apparent power, which is made of active power and reactive power. Power factor is the ratio of real power, measured in kW, to apparent power, measured in kVA. It shows how much of the supplied power becomes useful work. A low power factor often happens when an inductive load draws too much reactive power. This creates a lagging power factor. It can also cause large...

the power superposition principle

Power from Multiple AC Sources

Power from multiple AC sources is found by adding the effects of each source separately. In a circuit with two sinusoidal voltage sources, each source acts independently. The superposition principle says the total current is the sum of the currents produced by each source alone. If those currents are labeled i1 and i2, they combine to give the total current. Instantaneous power is the power at one moment in time. In this circuit, it equals the square of the instantaneous current times the...

the maximum power transfer theorem

Matching Load Impedance for Maximum Power

Maximum power transfer in an AC circuit depends on matching the load impedance to the Thevenin equivalent of the source network. The load draws current, and the circuit delivers power to that load. To analyze the current, the voltages, currents, network impedance, and load impedance are written in rectangular form. The average power delivered to the load comes from the square of the current multiplied by the load resistance. To find the condition for maximum power, the power is differentiated...

key terms and concepts

Learn how power factor correction improves AC efficiency by reducing reactive power, lowering voltage drops, and using series or shunt capacitors.

Reducing Reactive Power in AC Loads | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

Reducing Reactive Power in AC Loads

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